I have tried Google PSS (page speed service) and i have to say they will make your site super fast more than Cloudflare but they aggressively cache your site on their servers that some styles like my editor background color and fonts were not the correct ones.
Cloudflare has nice and simple features in term of optimization. But slow and because they are constantly under attack, sites on the free plan are suffering daily. Google PSS will make your site super fast and has much more optimization features but sometimes they will break some of your site styles. I also faced an issue on my forum, i was not able to login, it would say you have inserted the uncorrect password. Once I disabled PSS rewrites the issue was solved.
Have others had better experience with Google PSS and what do you think of Cloudflare?